Yes. There are quite a few variations of "privateness" documented in theDamian's excellent Object Oriented Perl. You can check the file and line number of caller, for example.

However, the moment you do that, I would not want to maintain your code. Every attempt I've seen at privacy has made the code more unmaintainable.

Just name your "private" methods with a leading underscore, and put "do not call outside of this class"
in a comment. People will get the idea, and they deserve what they get when they violate it. Why is that so hard to understand?

If your boss/client is so pigheaded that they won't see your well-reasoned point, quit. Get another job.

This advice isn't very realistic or helpful. It's easier said than done especially given the current market conditions. Besides, if everyone followed it, we'd all be working for the same two or three companies... and tilly would probably still walk among us.

Wow dude!! That was pretty loaded. And easier said then done ;) It's ALWAYS good to know all your alternatives.

A well reasoned point, incidentally, might be a long-lived software project with a large hierarchy of objects and a whole bunch of developers. It's a sad truth that some developers don't really care about good programming practices. Do you really want sloppy coders violating your well-designed system by making frequent calls to subroutines with underscores?

Bad coding practices sneak into the best of companies during crunch-times. And if it's the client's developers who are being sloppy, well...you don't have to be busness-trained to realize that dumping a paying client over the love of perl isn't in a company's best interest. Rather let them learn by example over time with gentil and wise encouragement.

"If your boss/client is so pigheaded that they won't see your well-reasoned point, quit. Get another job." - while everything else is unworkable the way you say, unfortunately this also does not work (round here, anyway). In fact, you can't even get another job, while at the same time caving in makes you less marketable anyway. Pointy haired rules OK! PML.

Ada Lovelace for the palindrome
Albert Einstein for having smelly feet
Alfred Nobel for his contribution to battlefield science
Burkhard Heim for providing the missing link between science and mysticism
Claude Shannnon for riding a unicycle at night at MIT
Donald Knuth for being such a great organist
Edward Teller for being the template for Dr. Strangelove
Edwin Hubble for pretending to be a pipe-smoking English gentleman
Erwin Schrödinger for cruelty to cats
Hedy Lamarr for weaponizing pianos
Hugh Everett for immortality, especially for cats
Isaac Newton for his occult studies
Kikunae Ikeda for discovering the secrets of soy sauce
Larry Wall for his website
Louis Camille Maillard for discovering why steaks taste good
Marie Curie for the shiny stuff
Nikola Tesla for the cool cars
Paul Dirac for speaking one word per hour when socializing
Richard Feynman for his bongo skills
Robert Oppenheimer for his in-depth knowledge of the Bhagavad Gita
Rusi P Taleyarkhan for Cold Fusion
Sigmund Freud for his Ménage à trois
Theodor W Adorno for his contribution to the reception of jazz
Wilhelm Röntgen for the foundations of body scanners
Yulii Borisovich Khariton for the Tsar Bomba
Other (please explain why)